Expensive weekly AMIP pipeline runs even when nothing has changed

[Sbozzolo]

The AMIP pipeline uses 1 GPU for 3 full days. The pipeline uses released version of packages, so, if no new versions are released, the same pipeline is run twice.

We can easily avoid this by adding a check before we run the pipeline: if the git hash is the same of the previous run, we skip the pipeline.

[Sbozzolo]

As a first step, I added an option to prevent the pipeline from running if no commits were added in the past week